Introduction:
Burst fire is when your gun fires a predetermined amount of shots with one trigger pull, and it is generally reserved for very limited AEG models with high price tags. Generally, it's a feature that you see on guns like Systema PTWs and the like. Avocado, a new company on the scene has manufactured a drop-up inline burst regulator chip giving you the ability to add burst fire to pretty much any AEG on the market for a very affordable price. I'll discuss all of the various features of this burst regulator in this review, so keep reading for more information!

Ordering:
I was sent this burst unit to review by Evike, who is Avocado's exclusive US distributor. It is available HERE, priced at $38 at the time of this review. It is covered by a lifetime limited warranty, so if you have any issues with the unit, it'll be covered. I received it 2 days after it was shipped out through USPS since it was such a small package.

Basic Information:
As mentioned before, the Avocado Burst Regulator is an inline burst controller that fits between your battery and AEG. This allows it to be installed on pretty much any AEG with the room to fit the compact unit. It is user programmable and able to be adjusted between 1 and 12 shots per burst, or 30 rounds per burst with the unit installed but deactivated. It also has features such as battery voltage monitoring to prevent damage to your battery from over-draining.

First impressions/Packaging:
The Avocado Burst Regulator is packaged in a plastic bag, attached to a glossy cardstock sheet with information about the unit itself. The packaging includes the features of the unit as well as the specifications including operating voltage, temperatures, etc.

From here on, click all pictures to enlarge
Packaging
Specs and features

Burst Unit Details:
There's really not much to say about the unit itself, aside from the fact that it has some pretty serious circuitry in a compact package. The earlier units were waterproofed in a sealed plastic wrapper, but the new model being reviewed today is in a hard plastic rectangular shell to keep it from getting damaged, however I don't think it'll provide waterproofing. The unit being reviewed today has two mini tamiya plugs, which is not the most electrically efficient design, but it does allow for a wider range of AEGs and batteries to be used in stock guns. I believe a Deans plug equipped unit will be available soon.

One side of the unit
The other side
Plugs

Installation is a piece of cake, only requiring you to plug it inline between the battery and gun. Once plugged in, you program it by setting the gun on full auto and pulling the trigger until the gun stops firing. At that point, keep holding down the trigger until the motor vibrates, indicating that the gun has entered programming mode. You can then pull the trigger the amount of times that you want it to burst with each trigger pull, followed by one last trigger pull that is held until the motor vibrates again. For example, for a three shot burst, you pull the trigger a total of four times, holding it on the last pull. For five shots, pull it 6 times, holding it on the last. You can set it up for a total of 12 shot burst using this method. To deactivate the unit, allowing a max of 30 shots, hold the trigger to enter programming mode, then hold the trigger once until the motor vibrates again. As I said before, it is a piece of cake to program this thing, only taking seconds.

Performance:
As far as performance goes, it functions true to your desired burst setting in the AEGs that I tested it in. I tested it in my G&G Combat Machine blowback M4, Javelin M4, Echo 1 RPK, Snow Wolf Thompson and M82A1, and the main gun that I'll be using to test it, the Classic Army LWRC Premium Sportline. On guns shooting over 25 RPS, you'll most likely need to set it one shot less than intended, so a total of three trigger pulls for 3 shot burst instead of four. You can set it to semi-auto only by pulling the trigger twice, holding it on the last shot. This feature is very handy for DMRs or other replicas that you want to restrict to semi-auto only.

Test gun
Inline installation

I used a 11.1v 1800 mAh 15C LiPo with that gun in my testing, and it worked fantastically. It gave me three consistent shots per trigger pull when I had it set to three shot burst. If you release the trigger part way through a burst, it will reset the burst cycle, so the next trigger pull is another set of three, for example.
One of the issues that I had was that the ROF was lower than without the unit, which I believe is due to the two additional mini tamiya plugs. I'll be switching mine over to Deans plugs to see if there is any difference in ROF. The other issue I had was with rapid fire semi-auto. The unit has built in voltage monitoring, so when your battery voltage gets too low, the gun will not fire, instead causing the motor to vibrate. When you pull the trigger too fast too many times on semi, the voltage can dip enough to trigger the voltage monitoring and cause the gun to stop firing for a second, until the battery normalizes. I tried it with a few different batteries and had the same issue, so it's something to look out for. Otherwise, the unit worked amazingly well.
Here is a video that I put together showing the unit in operation:

Pros:
Drop-in unit works with pretty much any gun
Incredibly easy to program
Very inexpensive – Sub $40
Adjustable for any amount of shots from 1-12, or 30 rounds in continuous mode
Gives you Systema PTW like performance for less than $40
Includes voltage monitoring to prevent damage to LiPo batteries
Small overall size, about the size of a fuse box

Overall:
I prefer burst fire to full auto, and that's why I like AEGs like the Type 89. I find that I have better ammo use, battery life, and even accuracy, as I choose my shots more carefully. This unit gives you programmable reliable burst fire for any AEG, something that before would have cost hundreds of dollars and require substantial installation difficulties. There are no timing issues that I've come across, as the unit uses voltage monitoring to determine when the gun fires, so it can accurately determine the burst timing. Overall, this is a very cool little unit that can be used for many different guns or situations, and I'm happy to have it installed in my guns!